Control device for induction heating

ABSTRACT

Photocells or other electromagnetic radiation-sensing devices are employed in combination with surface-hardening apparatus, which apparatus comprises an induction unit, a quenching unit, a support for an elongated workpiece and motors for moving and rotating the workpiece through the induction and quenching units, to control any or all functions of the apparatus.

United States Patent [72] Inventor Steven P. Kostyal Chicago. I11. 121 1 Appl. No 858,471 I22] Filed Sept. 16. 1969 I45 I Patented Nov. 23, 1971 73] Ansignee Park-Ohio Industries, Inc.

Cleveland, Ohio (54] CONTROL DEVICE FOR INDUCTION HEATING 2 Claims, 4 Drawing Figs.

[52] US. Cl 266/5 E, 219/502, 266/4 E [51] Int. Cl C2ld 1/10 [50] Field of Search 266/4 E, 4 S, 5 E;219/50.2, 10.57, 10.43

[56] References Cited V UNITED STATES PATENTS 2.202759 5/1940 Denneen et a1 .1 266/4 E 3.338,759 8/1967 Ledl et al... 266/4 S 3.351.740 11/1967 Heuer 219/502 3.435.173 3/1969 Connoy et a1. 219/502 3,495,777 2/1970 Evalds et al Primary Examiner-Gerald A. Dost Anomey- Meyer. Tilberry and Body ABSTRACT: Photoceils or other electromagnetic radiationsensing devices are employed in combination with surfacehardening apparatus. which apparatus comprises an induction unit, a quenching unit, a support for an elongated workpiece and motors for moving and rotating the workpiece through the induction and quenching units, to control any or all functions of the apparatus.

PATENTEDuuv 23 ml FIG. I

INVENTOR. STEVEN P. KOSTYAL BY Mew, 7114a), 61 Bad;

ATTORNEYS CONTROL DEVICE FOR INDUCTION HEATING The present invention pertains to the art of induction heating, and more particularly to improved apparatus for surfacehardening elongated metal workpieces by induction heating and subsequent quenching.

Frequently, it is desirable to surface harden elongated workpieces, such as axle shafts for motor vehicles. Most often the shaft or workpiece will be made of steel, but other quenchhardenable materials can also be treated in the same manner. Induction heating is generally employed for surface hardening because induction heating is easily controlled and uniform results are obtained.

The art of inductively heating elongated workpieces for surface hardening is well developed and has progressed to the point where workpieces of uneven cross section can be effciently surface hardened. For example, apparatus and process for surface hardening an elongated workpiece having a spadeshaped end are disclosed in U.S. Pat. No. 3,338,759. In the process described in the aforementioned patent, unifonn heating of the elongated workpiece is accomplished by passing the workpiece through an induction unit having a cross-sectional opening designed to receive the spade-shaped portion of the elongated workpiece. After the spade-shaped portion of the elongated workpiece passes through the induction unit the workpiece is then rotated to insure uniform heating of the circular portion of the shaft. Mechanical means are employed to actuate the rotating mechanism. The mechanical means comprise a cam mechanism with the cam surface being a part of the frame which supports the workpiece as it is passed through the induction unit. Although the apparatus and process described in US. Pat. No. 3,338,759 work reasonably well, the use of mechanical actuating means to control various function of the apparatus encountered mechanical drag with inherently slow response. In addition, if any change in the function of the apparatus is desired, the entire frame has to be replaced. Beside encountering the additional cost of replacement frames, it has been found that skilled labor is required to replace such frames. Although attempts have been made to overcome the foregoing problems and disadvantages, none, as far as I am aware, was entirely satisfactory when carried into practice on a commercial scale.

The present invention is directed toward an improved apparatus for controlling, either individually or in concert, the functions of individual components in a unit designed for surface hardening elongated workpieces.

In accordance with the present invention, there is provided improved apparatus for progressively and inductively heating a workpiece. The apparatus includes an inductor for inductively heating a workpiece, transfer means for establishing relative movement between the inductor and the workpiece so that the workpiece is progressively heated and electromagnetic radiation control means for controlling the heating operation in conjunction with the relative movement of the inductor and the workpiece by regulating either the inductor or the transfer means.

In another embodiment of the present invention, there is provided improved apparatus for quench hardening a workpiece. Such improved apparatus includes an inductor for inductively heating a workpiece, quenching means for quenching the heated workpiece, transfer means for establishing relative movement between the inductor and the quenching means and the workpiece so that the workpiece is progressively heated and thus quenched and electromagnetic control means for controlling the heating and hardening operations in conjunction with the relative movement by regulating the inductor, the quenching means or the transfer means.

In another embodiment in accordance with the present invention, there is provided an improved apparatus for surface hardening elongated workpieces. This apparatus comprises an inductor having a workpiece-receiving opening, a quenching unit with a workpiece-receiving passage, means for moving the workpiece progressively through the opening and through the passage and electromagnetic radiation means for controlling the operation of said apparatus in conjunction with the movement of the workpiece. Advantageously, the electromagnetic radiation means comprises a source of light with an intensity greater than daylight, e.g. infrared radiation, a photocell with a relay to control the desired function of the apparatus and a template placed and movable between the source and the receiver at a rate proportional to the movement of the workpiece through the induction and quenching units.

By providing surface hardening apparatus with the electromagnetic control means in accordance with the present invention, the elongated workpiece can be selectively surface hardened for any particular purpose. Since a template is employed to actuate the control means, any or all of the functions of the apparatus can be controlled by the electromagnetic control means of the present invention. For example, two photocells and one template having a predetermined pattern to actuate the photocells can be employed to control the operation of the induction unit and the quenching unit, either individually or in combination. Thus, in addition to providing a process for selectively surface hardening elongated workpieces the control means of the present invention provide rapid and varied control of all the functions of the apparatus while avoiding the time lag inherent in all mechanical control devices.

The primary object of the present invention is the provision of apparatus for surface hardening elongated workpieces which apparatus has improved control devices for controlling the function of the various units of the apparatus.

Another object of the present invention is a provision of apparatus for selectively surface hardening an elongated workpiece.

Still another object of the present invention is the provision of easily interchangeable devices in apparatus for surface hardening elongated workpieces.

These and other objects and advantages will become apparent from the followingdescription used to illustrate the preferred embodiment of the invention as read in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevational view showing, somewhat schematically, the preferred embodiment of the present invention;

FIG. 2 is an enlarged pictorial view depicting the template illustrated in FIG. 1;

FIG. 3 is a side view showing cross section of the template illustrated in FIG. 2; and

FIG. 4 is an enlarged view illustrating the elongated workpiece having a shaft and a disc member intermediately and concentrically mounted thereon.

Referring now to the drawing wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only and not for the purpose of limiting the same, FIG. I shows an apparatus for surface hardening an elongated workpiece. In accordance with the illustrated embodiment of the present invention, apparatus A is utilized for surface hardening of axle shaft B best shown in FIG. 4. The axle B, as shown in FIG. 4, includes a shaft portion 10 and disc member 12 mounted concentrically on the shaft intermediate the ends thereof.

Referring now in more detail to apparatus A, the apparatus includes an inductor 20 having a plurality of convolutions. three convolutions being shown, and a workpiece-receiving opening. The ends of the inductor are connected by leads 24, 26 onto a power source, schematically represented as generator 28. The flow of electrical current from generator 28 to inductor 20 is controlled by the control device 92, which will be described in greater detail hereinafter. It will be appreciated by those skilled in the art that although the control device 92 is shown as controlling the generator 28, the control device is fully capable of controlling other functions of the apparatus.

Apparatus A includes aligning centers 40, 42 secured onto frame 44, supported by appropriate means, not shown, for reciprocal movement in a direction parallel with the axis of axle B. The upper center 40 is secured onto the output shaft of a motor 46 which is energized by leads 46a and 46b to rotate the axle B. The lower center 42 is secured onto a pneumatically actuated cylinder 48. Axle B is loaded between centers 40, 42 by first retracting center 40, centering the workpiece, and then forcing the center 42 against the lowermost portion of shaft by introducing fluids, such as air, into cylinder 48. With the axle between the centers, movement of frame 40 downwardly will progress the axle through the opening of the inductor 20.

Although a variety of structures could be utilized for moving the frame in accordance with the illustrated embodiment of the invention, threaded nuts 50 are fixedly secured onto the frame 44 in a position to coact with a lead screw 52 which can be rotated by motor 54. The output shaft of motor 54 is rotated in a direction that will move frame 44 downwardly when the motor is energized by leads 54a and 5412. In like manner, movement of frame 44 upwardly is accomplished by energizing leads 540, 54c of motor 54. It will be appreciated by those skilled in the art that the control devices in accordance with the present invention can also be employed to control the movement of frame 44.

Below inductor there is provided a quenching unit 60 having a central workpiece-receiving passage 62. In accordance with the illustrated embodiment of the invention, the quenching unit 60 includes an internal fluid passageway 64 having a plurality of radially directed orifice 66. A conduit 68 is connected with passageway 64 and with quench fluid supply 70 so that quenching fluid flows from the supply 70 through conduit 68 into passageway 64. Thereafter the quenching fluid flows from orifices 66 in a radially inward direction to impinge upon and thus quench the previously heated portions of axle B. The quenching unit is actuated when current is supplied through control line 70a, 70b. When discontinuous portions of the workpiece, such as the disc 12, pass through the quenching unit 60, splashing may occur. Splashing of the quenching fluid upwardly against the inductor 20 and the workpiece being heated can cause defects in the heating operation. Therefore, it is highly advantageous to place splash shields 72 and 74 between the quenching unit 60 and the inductor 20. These splash shields are adapted to move inwardly and outwardly to permit passage of the disc member 12. After passage of disc member 12 through the splash shields, the splash shields can be again closed to avoid splashing into the inductor unit. Since the splash shields 72 and 74 are placed close to the inductor 20, it will be readily appreciated by those skilled in the art that the shields are preferably made of a nonmagnetic and nonconducting material, eg an electrical insulator. The movement of splash shields 72 and 74 can be regulated with the control devices of the present invention.

Referring now in greater detail to the control device in accordance with the present invention, it can be seen that the control mechanism comprises an electromagnetic radiation source 80 with leads 80a and 80b, and electromagnetic radiation receiver 88, an amplifier 90 and a relay 92 for controlling the flow of electrical current from the generator 28 to inductor leads 24 and 26. Template 82 with openings 84 is secured to frame 44 by thumbscrews 86. The template 82 is mounted on' frame 44 so that it moves in direct proportion to the axial movement of axle B through the inductor and quenching units. The electromagnetic radiation source 80 is advantageously a source of light, such as infrared radiation, while receiver 88 is advantageously a photocell of the cadmium sulfide type. Passage of template 82 with its preselected pattern openings 84 between source 80 and receiver 88 activates or deactivates receiver 88 which in turn activates or deactivates relay 92. Although H6. 1 illustrates the use of an amplifier, it will be readily appreciated by those skilled in the art that under certain circumstances no amplification of the current generated by the photocell is required.

Referring now to FIGS. 2 and 3 which illustrate the template in greater detail, when the combination of a source of light in a photocell are employed as the control mechanism, the template 82 comprises an opaque strip with a preselected pattern of openings 84. When light is employed as electromag netic radiation, the template 82 is made of a thin metal strip so that the preselected pattern of openings 84 can readily be punched in the strip.

The operation of the apparatus with the template affixed thereto in conjunction with the heat treatment of the shaft illustrated in FIG. 4, can be appreciated by reference to FIG. 1. From FIG. 1 it is apparent that as the center opening 84 passes between source and receiver 88, current generated by photocell 88 actuates relay 92 to permit current to flow from the generator 28 through inductor 20 to thereby heat the disc 12 mounted on shaft 10. In a like manner, the top and bottom openings 84 upon passage between source 80 and receiver 88 operate to actuate relay 92 which in turn controls the flow of current to inductor 20 to heat the ends of the shaft 10. Thus, the template illustrated in FlGS. 2 and 3 is effective in controlling the apparatus to selectively surface harden the ends of shaft 10 as well as only the disc member 12. Although the above description shows the operation of the inductor 20, it will be readily apparent to those skilled in the art that additional photocells along with additional openings on the template 20 would be effective in controlling other operations, such as the operation of the quench supply and/or the operation of motors 46 and 54. For example, the apparatus described in Us. Pat. No. 3,338,759 can be equipped with the control device of the present invention. Thus, when surface hardening an axle with a spade-shaped end in apparatus having an inductor with an opening designed to receive the spadeshaped end and having a motor to rotate the axle, the control device can control the motor to stop rotation of the axle during passage of the spade-shaped end through the inductor.

The present invention has been described in connection with one structural body; however, it is to be appreciated that various structural changes may be made in this embodiment without departing from the intended spirit and scope of the present invention.

Having thus described my invention, I claim:

1. An induction heating device for selectively heating portions along the length of an elongated workpiece having a central axis, said device comprising: a frame element including means for supporting said workpiece for rotation about said axis; means for rotating said workpiece about said axis; an in ductor element encircling said workpieceymeans for causing relative movement between said frame element and said inductor element in a direction parallel to said axis whereby said inductor element is moved with respect to said workpiece; control means connected to one of said elements for connecting said inductor to a source of alternating current only when said inductor element is opposite said selected portions of said workpiece, said control means including a source of electromagnetic radiation, a pickup means spaced from said radiation source, a control unit having a first condition when said pickup means is exposed to said source and a second condition when said pickup means is shielded from said radiation source, and means for connecting said source of alternating current to said inductor element only when said control unit is in one of said conditions; and, a movable control element fixed onto the other of said elements for movement with respect to said control means, said control element having spaced shielding means for causing said control unit to be in said one condition when said inductor element is adjacent said selected portions.

2. An induction heating device for heating selected first portions along the length of an elongated workpiece while selected second portions are unheated, said workpiece having a central axis, said device comprising: a frame element including means for supporting said workpiece on said frame element for rotation about said axis; means for rotating said workpiece about said axis; an inductor element having a central workpiece-receiving passageway; power means connected to said inductor element for energizing said inductor; means mounting said inductor with said workpiece extending through said passageway; means for causing relative movement between said frame element and said inductor element in a direction generally parallel to said axis; an electromagnetic radiation control device fixed with respect to one of said elements, said control device comprising a source of electromagnetic radiation, a spaced pickup means sensitive to the radiation of said source, a selectably actuated means having a first condition when said pickup means is exposed to said source and a second condition when said pickup is shielded from said source, means responsive to said selectably actuated means being in one of said conditions for disconnecting said power means from said inductor element and second means responsive to said selectably actuated means being in the other of said conditions for connecting said power means to 

1. An induction heating device for selectively heating portions along the length of an elongated workpiece having a central axis, said device comprising: a frame element including means for supporting said workpiece for rotation about said axis; means for rotating said workpiece about said aXis; an inductor element encircling said workpiece; means for causing relative movement between said frame element and said inductor element in a direction parallel to said axis whereby said inductor element is moved with respect to said workpiece; control means connected to one of said elements for connecting said inductor to a source of alternating current only when said inductor element is opposite said selected portions of said workpiece, said control means including a source of electromagnetic radiation, a pickup means spaced from said radiation source, a control unit having a first condition when said pickup means is exposed to said source and a second condition when said pickup means is shielded from said radiation source, and means for connecting said source of alternating current to said inductor element only when said control unit is in one of said conditions; and, a movable control element fixed onto the other of said elements for movement with respect to said control means, said control element having spaced shielding means for causing said control unit to be in said one condition when said inductor element is adjacent said selected portions.
 2. An induction heating device for heating selected first portions along the length of an elongated workpiece while selected second portions are unheated, said workpiece having a central axis, said device comprising: a frame element including means for supporting said workpiece on said frame element for rotation about said axis; means for rotating said workpiece about said axis; an inductor element having a central workpiece-receiving passageway; power means connected to said inductor element for energizing said inductor; means mounting said inductor with said workpiece extending through said passageway; means for causing relative movement between said frame element and said inductor element in a direction generally parallel to said axis; an electromagnetic radiation control device fixed with respect to one of said elements, said control device comprising a source of electromagnetic radiation, a spaced pickup means sensitive to the radiation of said source, a selectably actuated means having a first condition when said pickup means is exposed to said source and a second condition when said pickup is shielded from said source, means responsive to said selectably actuated means being in one of said conditions for disconnecting said power means from said inductor element and second means responsive to said selectably actuated means being in the other of said conditions for connecting said power means to said inductor element; and, a shield mounted on the other of said elements for relative movement with respect to said control device and in said space between said source and said pickup means, said shield having spaced openings therein, said openings corresponding to only one of said first and second portions of said workpiece whereby said power means is connected to said inductor element when said inductor element is opposite said first portions of said workpiece. 